Abstract:

Wood flour was treated with maleic rosin to improve its flow behavior, then compounded with high density polyethylene (HDPE) by an extruder to prepare wood-flour/HDPE composite (WF-HDPE). X-ray photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FTIR) techniques were used to study the change of the function group and element on wood flour before and after treatments. The rheological behavior of WF-HDPE composites were investigated by a rotary rheometer. XPS and FTIR spectroscopy analysis indicated that chemical bonds were formed between maleic rosin and wood flour through the esterification reaction of anhydride groups and hydroxyl groups on wood surface. Maleic rosin has been added to the surface of wood flour in the form of monoester, i.e., the formation of esterified wood flour bearing a pendent carboxylic group. The rheological study showed that the complex viscosity (η*), storage modulus (G′) and loss modulus (G″) of WF-HDPE composites decreased firstly and increased afterward and declined lastly as the dosage of maleic rosin increased, however, the viscosity of the composite melts decreased as a whole. After the modification of wood flour, the rheological properties of composite melts were improved markedly. According to the mechanical test it was indicated that, by proper treatment of wood flour with maleic rosin, the tensile strength and flexural strength of WF-HDPE increased obviously.

Key words: wood, maleic rosin, thermoplasticity, wood plastic composite, rheology